Harper, 18, has already proven he can play with professionals. He hit .319 with a .407 on-base percentage for the Nationals in the instructional league. He also led the team in several offensive categories, including hits, homers, RBIs and walks.

Harper then went to the Arizona Fall League and wasn't a disappointment, hitting .343 with a home run and seven RBIs for the Scottsdale Scorpions.

It was more than just the high batting average that impressed Nationals hitting coach Rick Eckstein. It was Harper's work ethic that blew Eckstein away. Harper spent the AFL season on the taxi squad, which means he could only play twice a week. In between games, Harper worked hard on his offense and defense, and the young outfielder acted as if he was going to play every day.

Eckstein was supposed to help refine Harper's swing, but there wasn't much to refine.

"He attacks the baseball, which is great for a hitter," Eckstein said. "The days that he wasn't playing, he treated those days as if he was playing. He would go out during batting practice and get reads off the bat in right field and center field. He was working to get better in the outfield. It was impressive watching him work.

"Obviously, in batting practice, he was doing well. He was lining the ball around the park and then driving balls [over the fence]. It was very impressive how he conducted his batting practices. He is very advanced at the plate. Mentally, he has a great feel for what he wants to do and a great work ethic for accomplishing it."

Harper, after putting up monster numbers in high school, received a lot of publicity last year when Sports Illustrated referred to him as the "Chosen One," and baseball's version of LeBron James.

Shortly thereafter, he turned more heads when he received his high school equivalency in lieu of becoming a junior in high school, then headed to the College of Southern Nevada to join a junior-college program that plays in a wooden-bat conference.

Having been used primarily as a catcher before being drafted, Harper is expected get to the big leagues sooner playing in the outfield. He is considered an above-average outfielder with a great throwing arm and speed.

In addition to the physical tools, Harper had the stats to warrant being taken No. 1 overall. In 2008 as a freshman at Las Vegas High School, Harper had a .599 batting average with 11 home runs and 67 RBIs in 38 games. He followed that up with a .626 batting average, 14 home runs and 55 RBIs in '09.

Playing against a high level of junior-college competition and hitting with a wooden bat didn't present much of a challenge to Harper, who hit .442 with 29 home runs and 89 RBIs during the 2010 regular season.